Building an open-source battery
FOSDEM 2025 featured the usual talks about open-source software, but, as always, the conference also offered the opportunity to discover some more exotic and less software-centric topics. That's how I learned about the Flow Battery Research Collective (FBRC), which is building what will eventually become an open-source home battery. Daniel Fernández Pinto represented the collective at FOSDEM with his talk "Building an Open-Source Battery for Stationary Storage" in the "Energy: Accelerating the Transition through Open Source" developer room (devroom).
The open-source battery
project has a close cooperation with Utrecht University's FAIR-Battery project and is
fully financed by
NLnet Foundation.
The FBRC is a relatively new project that started last year. Fernández, a chemist,
had been doing battery research at home and documenting his findings on a
blog since 2019. Electrochemical
engineer Kirk Smith discovered Fernández's blog and proposed joining forces. That led to the formation of a project to "build an
open-source battery aimed at solar and wind storage in the long term
",
while aiming to create kits for academic purposes in the short term.
Fernández started his talk with a brief explanation of how lithium-ion (Li-ion) batteries
work, since that is the battery technology most of us are familiar with. "In
lithium-ion batteries, we're basically just moving lithium ions from a graphite
substrate to a metal oxide.
" He underscored how thin such a battery is: the
cross-section is actually just a quarter of a human hair's thickness. "What
prevents such a battery from shorting is a 5µm separator
", he
elaborated. What we commonly refer to as a Li-ion battery is actually
composed of thousands of these layers packed and rolled together. The
advantage of Li-ion batteries is their high energy-density, but his
explanation was followed by the obligatory images of fires at large
battery installations. He noted: "any puncture in these tiny layers
and it all goes up in flames
".
Redox flow battery
Fernández then proceeded to describe an alternative type of energy storage: a
redox flow battery (RFB), which he characterized as "more robust for
large-scale energy storage
". The technology actually dates back to the
1980s. Rather than incorporating solid-state layers, a flow battery
consists of two tanks that store the reagents: a positive electrolyte (a
solution that accepts electrons) and a negative electrolyte (a solution
that donates electrons). Each tank has a pump, circulating both solutions
within their own circuit (tank and pipes), with a membrane in a cell in the
middle where the fluids
meet and exchange electrons. This approach is easily scalable: the tanks
can be enlarged if greater energy storage is needed, while the cell size
can be increased if more power is required.
Naturally, the question arises whether RFBs can compete with other battery
technologies. Fernández presented a chart with five variables: energy
density, power density, safety/sustainability, initial affordability, and
cycle life. This clearly illustrated that RFBs are not nearly as dense as
Li-ion batteries: "They have probably a tenth, or even a twentieth, of the
energy density of lithium-ion batteries.
" However, they hold significant
advantages in safety, affordability, and cycle life.
As for safety, RFBs are aqueous systems, "so they don't catch fire
". The
reagents are generally also more environmentally friendly than the
chemistry in Li-ion batteries, Fernández noted. Additionally, "if something
breaks in the cell, you can take it apart and replace it
", and the reagents
can be simply replaced if they stop working. "In a lithium-ion battery, any
small failure is critical and destroys the battery.
"
Why an open-source battery?
"There is currently no open-source battery initiative at all
", Fernández
stated, whether for Li-ion or flow batteries, hence the motivation for him
and Smith to establish one. He is aware of some other open-source projects
that aim to reproduce "just a cell
", but upon reading the research papers,
he realized that there's a lot of missing information, such as instructions
on how to build the pumps, reservoirs, and electronics.
Regarding this matter, Fernández said that flow-battery research faces
reproducibility issues: "a lot of researchers publish completely different
results because of their varying setups, and we wanted to create a cell
that could serve as a standard cell for flow battery research
". Even though
the FBRC intends to sell kits with battery cells, Fernández emphasized that
they want everyone to be able to build the cells on their own.
Roadmap
By the end of 2024, the FBRC had completed a bench-top battery cell, with a
cell area of less than 10cm², capable of supplying a low voltage and low
current. This will evolve into the kit that the FBRC plans to sell
"probably this year or next year
". As the project is open-source, buying
the kit isn't necessary, since anyone can build the bench-top cell following
the provided instructions. "We're currently testing chemistries and
different materials
", Fernández said, to deliver a kit with reproducible
results.
By mid-2025, the FBRC aims to have a large-format cell with a cell area exceeding 600cm², capable of supplying low voltage with a high current. Although this will still be a single cell, it should be scalable for larger-scale energy storage. Then, by the end of this year, Fernández hopes to have built a stack of tens of these large-format cells, capable of supplying the high voltage and high current to power a house.
The goal is to replicate something akin to Redflow's ZBM3, which is a 10kWh
zinc-bromine flow battery with a continuous power rating of 3kW. Fernández's
mention of Redflow was no coincidence, the company went bankrupt at the end
of 2024, and that is part of why he's so keen to make an
open-source battery. "Redflow invested a lot of time in these cells, which
are pretty good. If this had been open-source, people could've used the
knowledge to start other businesses, or even build the batteries
themselves.
"
The cheapest pump that works
Fernández also described some of the prototypes that they built. The first
prototype of the battery cell was intended to be built from polypropylene,
with silicone gaskets and small diaphragm pumps, but the design had
numerous possibilities for leakage and other problems. They actually
3D-printed this design with resin, "because we never managed to print
polypropylene well enough
". Regarding this initial design, Fernández said: "None
of this worked. The tubing didn't work, the cell didn't work, the pumps
didn't work.
" To control the pumps, Fernández used an Arduino and an
inexpensive motor driver "in total costing less than 20 euros for the
electronic part
".
In the second attempt, they had polypropylene bodies manufactured, and the
diaphragm pumps were replaced by peristaltic pumps. The design saw several
improvements, and Fernández showed a video of the pumps in operation, adding
"that pump is not supposed to be orange
", but was, because it had
leaked orange
fluid. This was all conducted in Fernández's apartment, he said, joking that he
was still standing, "so it's not that dangerous
".
Then they changed to a second design trying to prevent the leaks, and the
pumps were changed once again. Fernández explained this choice: "We began with
the cheapest possible pump we could get, I broke it, and then we moved to
the next one. I've been doing that iteratively, breaking every tier of
AliExpress pump until I had the cheapest model that works.
"
This second design worked pretty well, initially with Zinc-iodide as the
chemical, since this is readily available in the EU without requiring a
license to buy chemical materials. "It's not like you can drink it, but
it's not extremely toxic
", Fernández added. They did some tests, and this
design yielded around half of the energy density of commercial flow
batteries.
In flow-battery research, the membrane in the middle is traditionally an
expensive Nafion membrane. In contrast, the FBRC's design uses "a very
fancy microporous membrane that's called photopaper
". According to Fernández,
this still exhibits some leakage and resistance, explaining that the
resulting energy efficiency of 65% is not particularly high, "but it's very cheap
to achieve
".
Following this, Fernández showed that they can also achieve higher densities,
"at the level of a commercial flow battery
", although the graph stopped at
two discharge cycles because other parts of the system failed at that
point, such as the
tubing and pumps: "As things become more energy-dense, they become more
reactive. We only had two cycles here because of the corrosion.
"
Thus, for the next step, they acquired a beefier, impeller pump "the size of a
fist
". While the previous pumps could pump 60 milliliters per minute, this new pump manages 6000mL per
minute, which is necessary to scale up to the large-format cell.
Getting involved
Fernández concluded his talk by describing some ways to get involved in the
project. Firstly, individuals can assemble a kit using the online
documentation. "Nobody has attempted this, so we're not sure if the
instructions are any good
", Fernández joked, adding that "we want to
make the documentation better
". Additionally, just testing whether
3D-printing the pieces works is also valuable "because we need to make
sure that the pieces can be printed on a range of printers and with
different materials
".
Similarly, individuals can also assist by testing various tubing materials
or pumps. Additionally, when the project scales up soon, building and
testing larger-scale cells will be useful, although Fernández advised that this
should only be done with water "because we don't want anyone to die
helping us
". Lastly, from an electronics standpoint, the project doesn't
have a battery management system yet, which is essential for
larger-scale flow batteries.
The Flow Battery Research Collective is an intriguing initiative to develop an open-source home battery. Fernández and Smith have clearly focused on an approach that is affordable, safe to handle, and with parts and chemicals that are easy to source. Hopefully their projects can make battery research reproducible and help to democratize home batteries.
[While I was unable to attend FOSDEM in person, I watched the live-stream of the talk.]
| Index entries for this article | |
|---|---|
| GuestArticles | Vervloesem, Koen |
| Conference | FOSDEM/2025 |
Posted Feb 26, 2025 18:44 UTC (Wed)
by Cyberax (✭ supporter ✭, #52523)
[Link] (17 responses)
The main issue is the membrane, it just doesn't work. The power density is very low, so you need a large area, and so you have to use a fairly thick membrane to withstand the mechanical forces of the flowing electrolyte. But that forces you to place electrodes a bit more far apart, so the internal resistance of the cell becomes too large, and your efficiency craters.
Increasing the concentration of the reagents in the electrolyte also is problematic because it increases the osmotic pressure, resulting in (you guessed it) a thicker membrane that can withstand it. One of the startups tried to go this route, but their membranes just couldn't last long enough to be commercially viable.
In addition, the electrolytes are usually corrosive, especially the "charged" ones, so you have to use expensive stainless steel and other corrosion-resistant materials throughout the system.
Posted Feb 26, 2025 20:22 UTC (Wed)
by malmedal (subscriber, #56172)
[Link] (16 responses)
People kept thinking that lithium-batteries could not possibly get any cheaper, and then they did just that. I remember a study claiming the theoretical minimum was $300/kWh. (current price is less than $50)
It reminds me of how people kept thinking that Silicon could not get any faster and next year we'd finally get GaAs chips.
Posted Feb 26, 2025 21:08 UTC (Wed)
by Cyberax (✭ supporter ✭, #52523)
[Link] (1 responses)
I think that something like a sodium-ion battery will end up dominating the energy storage business.
Posted Feb 26, 2025 21:43 UTC (Wed)
by malmedal (subscriber, #56172)
[Link]
Only downside is that sodium is heavier, but I heard some rumours that it can withstand more charging cycles.
Posted Feb 26, 2025 22:14 UTC (Wed)
by Wol (subscriber, #4433)
[Link] (13 responses)
There's a difference between getting faster (a physical constraint) and getting cheaper (an economic constraint).
You cannot clock your standard ATX motherboard faster than 500MHz (or CPU faster than 1GHz) because speed of light. (As people have pointed out to me, there are ways to cheat ...)
But just because we can't (curently) make things cheaper, doesn't mean we can't find a way. Big diamonds were expensive. Now we can grow them cheaply ... artificial rubies likewise ... making petrol was wasteful of oil which meant diesel was cheaper, now cracking can make petrol as cheaply as diesel ...
But if the Physics says "this won't work", you're stuffed (unless you find a cheat). Don't worry, nature cheats too - we wouldn't have stars if it weren't for a cheat ... :-)
Cheers,
Posted Feb 27, 2025 8:42 UTC (Thu)
by PeeWee (guest, #175777)
[Link] (12 responses)
There seems to be a misunderstanding. Of course you can and we do. CPUs these days top out at around 5GHz and that is real clock speed, not "cheated". The problem which involves the speed of light is called "clock skew": at such high frequencies the distances the clock signal needs to travel in the circuitry become very relevant. Just take one clock cycle at 1 GHz (forget about rate doubling). That is 1 nanosecond per cycle. And the speed of light is somewhere around 2/3 of the vacuum speed in these materials. This makes it very non-trivial to ensure that the clock signal reaches every subsystem at the same time and CPU vendors expend significant compute resources to match up the clock line lengths, to make sure it does.
The other problem with increasing clock speeds has to do with parasitic capacitors and resistors; every transistor gate has a parasitic capacity and every electrical line has a parasitic resistance. Both multiplied are: R*C or just RC, for short. That should look familiar to some people and it also has a name: "time constant" (symbol: Tau, the Greek letter). This defines how fast one can load a capacitor and has a bearing on how steep the edges of the clock signal are. Ironically, what we draw (idealized) as rectangular clock signal with infinitely steep edges is more like a sine wave in reality due to this. And if one clocks too fast the signal might not even reach full nominal voltage. One can, of course, increase the voltage, but since that increases power consumption, i.e. heat, there is an upper limit, because the cooling has its limits as well. Also power is proportional to the square of the voltage, and higher voltage means a higher likelihood of breaking through, and thus destroying, the transistor gates. And that's the reason for the 5 GHz limit, which is already higher than originally anticipated. But there is simply no way to make any more gains in this area with the given materials, other than ever decreasing incremental ones.
Posted Feb 27, 2025 11:12 UTC (Thu)
by Wol (subscriber, #4433)
[Link] (11 responses)
That's the point. That is the time required for a signal to travel from one side of a mobo to another. So in order for a component to receive a response - ANY response - from a component on the other side of the mobo - it's impossible for the mobo to run faster than 500MHz. A chip is an order of magnitude smaller, so it can run an order of magnitude faster.
Getting round the speed of light is what I meant by "cheating". You mention making sure the clock signal arrives everywhere at the same time. CPUs have pipelines. Etc etc. But at the end of the day, if you want two components to talk to each other, you have to assume that that communication cannot happen faster than 500MHz without "cheating". Be it squeezing components as tightly together as possible, predictive pipelines, all sorts of fancy tricks to give the illusion of faster than light.
Cheers,
Posted Feb 27, 2025 11:28 UTC (Thu)
by PeeWee (guest, #175777)
[Link] (5 responses)
Posted Feb 27, 2025 14:51 UTC (Thu)
by dskoll (subscriber, #1630)
[Link] (4 responses)
The external clock frequency supplied to a CPU is much less than the internal CPU clock frequency; I think it's this external clock Wol was referring to. The internal clock is generated via a clock multiplication circuit and a PLL.
Posted Feb 27, 2025 15:07 UTC (Thu)
by Wol (subscriber, #4433)
[Link] (2 responses)
But if you don't want to stall the bejeezus out of your chip, you can't go any faster than that ... (without pipeline/magic "cheating" etc etc.)
Cheers,
Posted Feb 27, 2025 16:56 UTC (Thu)
by kleptog (subscriber, #1183)
[Link] (1 responses)
10Gb/s ethernet over copper has multiple bits "in-flight" on the cable if it's more than a few metres long.
A technical challenge sure, but not impossible.
Posted Feb 28, 2025 9:22 UTC (Fri)
by taladar (subscriber, #68407)
[Link]
Posted Feb 27, 2025 16:10 UTC (Thu)
by atnot (subscriber, #124910)
[Link]
Posted Feb 27, 2025 13:52 UTC (Thu)
by farnz (subscriber, #17727)
[Link] (4 responses)
Where size becomes an issue is where latencies are critical - if a device is small, everything can be assumed to happen in a single clock cycle, but as the scale increases, the minimum latency also increases. You thus have an extra layer of complexity when clocks increase, because you can no longer place devices freely; you have to allow for latency issues.
But all this actually means is that various simplifying assumptions that hold at 20 MHz stop holding at 200 MHz, and simplifying assumptions that hold at 200 MHz don't hold at 200 GHz. Instead, as the frequency increases, the amount of real-world physics you have to take into account also increases.
Posted Feb 28, 2025 9:26 UTC (Fri)
by taladar (subscriber, #68407)
[Link] (3 responses)
Posted Feb 28, 2025 10:19 UTC (Fri)
by farnz (subscriber, #17727)
[Link] (2 responses)
As frequency increases, you quantise the possible latencies of an operation into more buckets; a signal travelling 2 cm in a typical chip takes about 0.1 nanoseconds to do that (speed of light in a silicon chip is about 2/3rds of that in a vacuum). If your clock cycle time is 1,000 nanoseconds, then it's easy to ensure that everything in your chip is at most half a cycle time away from everything else.
But if your clock cycle time is now 0.2 nanoseconds (5 GHz), you have to place the latency sensitive parts with care; you need the things that cannot wait more than 1 clock cycle to be safely under 4 cm apart at their furthest extents, because even 4cm is too far to be reliable (since logic has its own delays and required timings to meet when the signal enters and exits part of the chip). You can put things that can tolerate a 10,000 cycle delay at 5 GHz on different chips on a motherboard, since your 10,000 cycle delay is 2 microseconds, giving you about 300 meters, even as you put things that cannot tolerate more than 1 cycle latency 2 cm apart.
Note though, that this doesn't make 5 GHz impossible on a chip that's 80mm by 80mm; it just means that you have to work a lot harder on chip layout for a 5 GHz chip than you do for a 2 GHz chip of the same size.
Posted Feb 28, 2025 11:50 UTC (Fri)
by malmedal (subscriber, #56172)
[Link] (1 responses)
The speed you can signal on is governed by the telegraphers equations.
The answer is complicated and depends on the process technology. In 28nm I believe the typical speed of signal propagation is around 20% of light-speed, there are things you can do on the chip to make it faster, at the cost of space and power.
Posted Feb 28, 2025 16:26 UTC (Fri)
by malmedal (subscriber, #56172)
[Link]
This article gives a speed of 1200 ps/mm for a 5nm node:
https://semiengineering.com/slower-metal-bogs-down-soc-pe...
speed of light is 3.3ps/mm...
Posted Feb 26, 2025 22:17 UTC (Wed)
by jcorgan (subscriber, #47213)
[Link] (1 responses)
With vehicles, mobile phones, and small devices, storage density and lack of maintenance are paramount. Lion and its variants have proven able to provide high density storage in a form factor that is suitable for this (large) niche, and are unlikely to be displaced except for non-technical reasons like supply chain issues or cost. Sodium-based batteries seem to be gaining and might find a place alongside where their somewhat lower power density is acceptable.
But (for the reasons put in the article) stationary battery requirements relax many of the constraints Lion batteries have, and allow optimization in several directions. Flow batteries don't have the weight issues, can decouple power, voltage, current, and capacity into their own more easily scaled dimensions, can allow maintenance, upgrades, and "top ups", and don't present many of the safety issues that lion batteries have. They'll never be in your phones or cars, but they might provide load leveling for the building you work in, your off-grid home, or your entire city.
Most of the challenges in the article seem like well understood mechanical engineering issues (pumps, corrosion) that need to be solved on the scale of an open-source laboratory kit, the exception being the separating membrane. That one is tough for everyone and at the individual-researcher-in-a-lab scale it is likely the most difficult part of this project.
It's exciting to see this technology finding a home in an open source type of community, and really wish this group success.
Posted Feb 27, 2025 9:15 UTC (Thu)
by taladar (subscriber, #68407)
[Link]
Posted Feb 27, 2025 7:59 UTC (Thu)
by PeeWee (guest, #175777)
[Link] (43 responses)
Just do a back of the envelope estimation of how big such a thing needs to be to power a household for a day, as in 21 kW (kilowatts) power capacity, which is the power capacity of a bog-standard household grid connection where I come from - it need not necessarily be able to run at that level all the time but must be able to provide that much power if one wants to minimize changes to the electrical installation. A standard household in Europe uses somewhere around 4000 kWh (kilowatt-hours) of energy over the year - without such energy guzzlers like electric cars and their chargers which would most likely at least double the demand -, so, let's say, on average 10 kWh per day, to make it a nice round number. I know, such numbers make US-Americans laugh, since they play in the "big leagues", right?
With these crude basics and their data the energy portion of the equation is something like:
That is only the energy part and the bare minimum of being any kind of useful. Since we are talking about aqueous solutions, let's take the mass density of water, so one would need 1 m³ of the reactants. And Vanadium is rather rare, IIRC.
Add to that the moving parts (pumps), which you never want in such things as a battery. Also the fact that the reactants keep destroying them, the tubing and gaskets speaks very loudly about them being hazardous material, even though less so (maybe) than Li-ion battery chemistry, but hazardous nonetheless. It also makes me question their qualifications, if they cannot even get the right material which withstands such chemicals. That looks like Chemistry 101, maybe 201, but then I am not a chemist, yet one of the authors claims to be one IIRC.
And these are just some of the alarm bells to see that this doesn't scale, at all. And it will not be cheap, even if the teething problems get solved, because the solution to those is most likely some pricey and/or rare materials. It's just one more excuse for people to not ask, let alone answer, the tough questions about our wasteful lifestyle. At this point I am rather inclined to just call it a century and not bother anymore with trying to fix humanity. I won't live long enough to see the worst of the consequences and have no children to whom I would have to explain why we leave them their earth - which we just borrowed from them, remember? - in such increasingly uninhabitable state.
Posted Feb 27, 2025 11:20 UTC (Thu)
by kleptog (subscriber, #1183)
[Link] (2 responses)
Europe is densely populated and has high-tech capabilities, so there will need to be completely different solutions there. If you have a lot of EVs then you don't need as much grid storage since they are interchangeable to some extent. Charging an EV from a grid-battery is a terrible idea.
As an element vanadium is as common as zinc in the Earth's crust, more common than copper, though not as easily available in concentrated ores.
I agree things aren't looking great right now, but just giving up doesn't seem like a good idea either.
Posted Feb 27, 2025 12:00 UTC (Thu)
by malmedal (subscriber, #56172)
[Link]
In one of those places(Congo), I once asked why they did not buy solar cells, it would be much cheaper than buying gas for the generator. The answer was that the security situation was such that they would be broken or stolen in short order.
> I agree things aren't looking great right now, but just giving up doesn't seem like a good idea either.
Things are looking great from a purely technical/economical perspective, batteries plus solar is the cheapest power you can get in most of the world. A full transition to renewables is technically easily within reach. Politically, not so much.
Posted Feb 27, 2025 12:10 UTC (Thu)
by PeeWee (guest, #175777)
[Link]
Yet they are trying where commercial efforts evidently have failed multiple times already.
> No, hobbyist setups aren't going to take over the world. But if you can make an open-source flow battery setup that works with commercially available materials
They seem to be finding out that it can't be done, is my point. Why would hobbyists have an advantage if the materials are commercially available? Industrial scale producers can buy those in bulk and even negotiate quite significant rebates, which Joe Public simple can't.
> that's a huge deal for the large parts of the world where a commercial flow battery sales person is never going to go (i.e. large parts of Africa).
One of the preconditions seems to be a 3D-Printer including the right raw materials. Lots of those in Africa I guess. :p
> As an element vanadium is as common as zinc in the Earth's crust, more common than copper, though not as easily available in concentrated ores.
And therein lies the rub. And it is already in demand because of steel alloys for high quality tools, e.g. Chrome-Vanadium-Steel wrenches. Additional demand at scale will drive the prices up. But this was only one example taken from their slides. Other materials will have the same problem though. Plus, how much energy goes into making them, cradle to cradle, if we include recycling, of course? People keep forgetting that money is a flawed measure. The laws of Physics know no dollar signs.
> I agree things aren't looking great right now, but just giving up doesn't seem like a good idea either.
My point is more about these kinds of pseudo-solutions to give false hope to Star Trek victims, hence my dig about "teching out of the problem". Some writer once spilled the beans on how to write Star Trek episodes, roughly like so: "write a run of the mill ordinary story and when it comes to a head we will tech our way out of it - enter Geordi La Forge". That's basically the modern equivalent of "Deus Ex Machina" in ancient Greek dramas: humans are at an impasse and the "God from the Machine" intervenes.
And if we *keep* falling for this kind of "solution" we may as well call it quits and have one big demolition party. There is a great skit from German TV suggesting just that, but I have not found an English equivalent; it's called "50 awesome years - the long demolition party" - spoiler alert: "Anyone still procreating is an asshole" (for putting their children through this). By extension, anyone suggesting that we can tech our way out of this, without even considering reducing our energy/resource demand footprint, is an asshole as well, or just an idiot or both.
Posted Feb 27, 2025 11:30 UTC (Thu)
by malmedal (subscriber, #56172)
[Link] (9 responses)
Did you read the article? They explicitly say that they are trying to find the cheapest solution that actually works.
Making an expensive flow-battery is a solved problem. They work just fine for stationary storage, only reason not to buy them is that LFP is cheaper.
Posted Feb 27, 2025 12:21 UTC (Thu)
by PeeWee (guest, #175777)
[Link] (8 responses)
I even watched the presentation. It's just that the approach seems very flawed. Also it was about the cheapest pumps in the presentation. A chemist should know up-front the interactions between the reactant and the tubing/housing/etc. chemicals, which begs the question, why they keep doing the trial and error for no apparent reason on that front.
> Making an expensive flow-battery is a solved problem.
If going bankrupt is an acceptable solution.
> They work just fine for stationary storage, only reason not to buy them is that LFP is cheaper.
Read that sentence aloud ten times. That should help you understand what you just said. ;-)
Posted Feb 27, 2025 13:04 UTC (Thu)
by malmedal (subscriber, #56172)
[Link] (4 responses)
>Read that sentence aloud ten times. That should help you understand what you just said. ;-)
Sigh, please read what I wrote. I am saying that LFP-type cells are cheaper than flow batteries and this is the reason you wouldn't want to buy the latter at the current time.
Posted Feb 27, 2025 13:11 UTC (Thu)
by PeeWee (guest, #175777)
[Link] (3 responses)
Posted Feb 27, 2025 13:29 UTC (Thu)
by pizza (subscriber, #46)
[Link]
You forget that LFP started out as more expensive than standard LiIon cells.
Every new technology starts out more expensive (on a per-unit basis) than existing tech.
Posted Feb 27, 2025 13:42 UTC (Thu)
by malmedal (subscriber, #56172)
[Link]
Posted Feb 27, 2025 13:50 UTC (Thu)
by farnz (subscriber, #17727)
[Link]
Similar logic applies to flow batteries; in theory, they have a much lower self-discharge rate and higher lifetimes than LFP, but we need to overcome the practical issues first. Now, given where we are with the ongoing climate crisis, commercial interest should be targeting mostly LFP - the current urgency is to build out so that we can decouple electricity use from generation over a 24 hour period, and LFP is good for that - but having people try to overcome the issues with flow batteries so that we have a good option to decouple over a 12 month period is also good.
Posted Feb 28, 2025 8:09 UTC (Fri)
by marcH (subscriber, #57642)
[Link] (1 responses)
I spent 5 min googling and found this:
- Some flow batteries are already cheaper / kWh
This seems to confirm stuff I had already read before.
Different battery technologies have different trade-offs and there's always been more than one technology successful at the same time.
I don't know why that company went bankrupt but it does not seem to be the rule.
I recommend you spend less time writing and more time researching.
Posted Feb 28, 2025 8:22 UTC (Fri)
by marcH (subscriber, #57642)
[Link]
For completeness:
It's a very complex field evolving very quickly.
Posted Feb 28, 2025 14:32 UTC (Fri)
by chatcannon (subscriber, #122400)
[Link]
This expectation is unrealistic. A chemist can calculate from readily available data whether such a reaction is thermodynamically possible (i.e. whether it results in an increase in entropy). In the vast majority of cases the answer is yes for at least one of the pairs of chemicals present, but that doesn't say anything about the rate of the reaction. Sometimes the reaction will be so slow that you can ignore it, other times it isn't. Maybe the presence of a third chemical helps to catalyse the reaction. It's very possible that you are the first person who has ever been interested in this particular combination of chemicals and, even if you are not, chemistry data are often only available through expensive proprietary subscriptions, much more so than in other sciences.
That's before you consider that when you buy something labelled as "polypropylene tubing" you don't know the chain length distribution or tacticity of the main polymer, or what plasticizers or other additives it might contain. One brand might contain a plasticizer that reacts with the electrolyte, rendering the tubing brittle over a period of weeks or months, whereas another brand of ostensibly the same material might last much longer. So it's entirely reasonable to use a trial-and-error approach, after using your chemistry knowledge to rule out obvious failures.
Posted Feb 27, 2025 11:53 UTC (Thu)
by NRArnot (subscriber, #3033)
[Link] (8 responses)
The loading on a concrete pad is probably the biggest issue after reagent environmental safety, but 2 tonnes/square metre isn't hugely problematic.
Posted Feb 27, 2025 12:00 UTC (Thu)
by paulj (subscriber, #341)
[Link] (6 responses)
Currently, have to sell excess solar energy in the day to the grid at about half the price (or worse) that we then have to buy that energy back at in the evening / night. Which.... sucks. If we could store that energy with >70% efficiency, that'd be nice. In an *ideal* world, I'd want ability to store at least a few months worth of energy, for at least 6 months - cause (obviously) our excess solar production is biased to one time of year (summer), while much of our energy demand is biased to another (winter, heating).
Posted Feb 27, 2025 15:44 UTC (Thu)
by jjs (guest, #10315)
[Link] (5 responses)
(electricity price) = (cost of electricity production) + (operating costs to include maintenance & upgrades of grid) + (profit)
Net metering sets (cost of electricity production) = (electricity price).
Converting the equation:
That equation only works if not only is (profit) = 0, but (operating costs) = 0. Which won't happen.
Net metering works when the percentage of customers on net metering is on the order of 1% or less. As the number of customers who also are providers grow, the grid operators have to either end net metering, or go out of business (i.e. you no longer get electricity).
The best way to store electricity long term is spread the cost - by both aggregating the storage (so any one customer only has a small amount of the cost), and spreading the location (i.e. interconnect) to minimize the storage actually needed.
Posted Feb 27, 2025 21:00 UTC (Thu)
by marekm (subscriber, #174682)
[Link] (4 responses)
Some examples:
Many washing machines and dishwashers have a feature where they can start automatically at preset time of day. Most ordinary households don't bother using this as they pay fixed price per kWh 24 hours a day. If they had reduced prices around noon in the sunny months of the year, they would have an incentive to read the fine manual and learn to use this feature to get some savings. It is possible to choose a tariff with lower off-peak prices, but then the peak prices are higher so on average there isn't much difference unless you can really put most of the energy demand during off-peak hours (not many people can).
People who drive electric cars for their daily commute from home to work and back (not all work can be remote), often charge their cars at home overnight because of very high kWh prices on fast public chargers. Instead the employers should get incentives to install more slow chargers (basically just simple AC power sockets) on their parking lots, for cheap slow charge during the day when there is excess solar. No need for high power fast charge as the car is parked when the driver is at work for a few hours, enough for the typical 20% to 80% slow charge to go home and back to work. Of course this assumes electric cars become cheap, small city cars - it needs to be literally the people's car (German: Volkswagen) and not a very expensive large and power-hungry SUVs and a status symbol to say "I'm rich". More like Dacia Spring or Leapmotor T03 (offered only recently), not Tesla or Mercedes.
Doing these fairly simple and cheap things would allow much more net metering, the problem is really that grid operators are monopolies and want to maximize their profits "because they can" and have too much political power, while net metering is good for the consumers and money saved on energy bills could be spend elsewhere which is good for the economy in general (of which grid operators are only a small part). But grid operators really want high profits, and prefer to shut down solar plants (waste the renewable energy) when their is too much sun, instead of putting that excess energy to real good use as shown above.
Poland (where I live) has had net metering until March 2022, PV installs made before that date can keep it for the next 15 years and it's a very good thing (basically storing energy in the grid for up to one year with 80% efficiency), sadly not an option anymore for anything new installed after that date. The only option for new installs is much less favorable net billing, which is also much more complex to calculate if it's profitable for the consumer at all. Before our 2023 elections the new ruling party promised to bring net metering back (item 84 of https://100konkretow.pl/wszystkie-konkrety/ ) but they haven't, instead trying a few times to patch the new net billing system with little real improvement, just trying to show they do something. Apparently impossible due to EU regulations as they say, but still was possible for the Netherlands which is also in the EU - it's just that their parliament was more in favor of the people, not the grid operators.
Posted Feb 27, 2025 21:26 UTC (Thu)
by malmedal (subscriber, #56172)
[Link]
Posted Feb 27, 2025 21:48 UTC (Thu)
by kleptog (subscriber, #1183)
[Link] (2 responses)
Why? Because net metering means that energy companies have buy expensive electricity in winter to match the cheap electricity they bought off you in the summer. (You get to net meter, but your energy company doesn't.) As a result, energy companies make a loss when customers have solar panels, which then has to be compensated by a higher per kWh price for everyone.
So the whole system is essentially a massive subsidy from people without solar panels to people with solar panels. One in three Dutch houses has solar panels, and since it's generally the more wealthy people who own their own houses that install solar panels, poor people are basically subsidising rich people. It also removes any kind of incentive to install batteries or manage your electricity usage.
Of course, the new government said they kept net-metering so that poor people could also benefit, except people renting or living in social housing or apartments can by construction never benefit from this scheme (facepalm).
So yeah, "net metering is good for customers" if you're rich enough to live someone where it's possible.
(Near as I can tell there's no EU directive explicitly forbidding net-metering, but the Renewable Energy Directive II does say things like that batteries should be promoted and costs of the energy transition fairly shared, and net-metering goes against both of those.)
Posted Feb 27, 2025 23:01 UTC (Thu)
by marekm (subscriber, #174682)
[Link]
Most people with their own houses are paying for them with high interest rate mortgages, so they are not really that rich (myself included), the interest rates here are among the highest in Europe, banks are making a lot of money "because they can" much like the utilities. It's often around 10% per year interest rate when you borrow from the bank, and next to nothing when the bank borrows from you (you keep your money in the bank, except short time promotions like "new money for the first month").
So it's the energy companies and banks who are very rich here (and they likely also sponsor some politicians to keep the status quo), while solar panels are quite popular among average-rich people (someone really rich doesn't need them, really rich people could simply pay their high energy bills and enjoy a cleaner looking roof).
Adding extra fees for those producing more solar power is downright evil, especially if based on total size of solar panels (their theoretical max power if always perfectly aligned to the sun) and not just peak power sent to the grid. So I'd be actually punished for adding more east/west panels (or vertical bifacial ones that could double as a fence) that make more energy during the early/late hours when there is more demand.
Posted Feb 27, 2025 23:27 UTC (Thu)
by Wol (subscriber, #4433)
[Link]
My home has effective "net metering", although that's because I've got an old-fashioned mechanical meter that runs backwards if I'm generating more than I'm using, and that's an "improper combination" - you're supposed to get a smart meter if you have an array, and they don't run backwards.
So if you get an array in the UK, what is (or was) supposed to happen is you got a "generation payment". There's a meter on your solar output and you get paid a decent sum for your generation (to pay back the capital cost of you installing the arrays). Because smart meters couldn't go (or measure) backwards, they then assumed that you kept 50% of your generation and fed the other 50% into the grid, for which you get paid a nominal sum. You can now get "feed in" meters so you get paid for the actual electric you feed into the grid.
Over the years the generation payment has dropped as panels have got cheaper, and you can't get it for new installs any more I don't think. The feed-in payments are pants, so basically you now pretty much want to use most of the power you generate.to get your money back. But the panels are cheap, so it's roughly worth it. I'm getting good money on all three arrays, but that's because they're old and the generation payments will expire in the not too distant future. So the only benefit I will get once that happens is a bit of feed-in money, and a bit of free electric. It is what it is, but it still seems economic for people to install panels ...
Cheers,
Posted Feb 27, 2025 12:41 UTC (Thu)
by PeeWee (guest, #175777)
[Link]
Posted Feb 27, 2025 11:57 UTC (Thu)
by farnz (subscriber, #17727)
[Link] (17 responses)
Setting the scene, we have two factual statements:
This leaves us with a niche to fill; we need something that can absorb energy when we have excess renewables available for more than 24 hours, and then release it months later when renewables hit what the Germans call a "dunkelflaute" - insufficient insolation and no wind over a long period, causing a shortfall in energy - and this niche is where flow batteries are interesting.
Something that fills this niche does not need high power potential - you'll still have your short-term batteries available, so you're filling those steadily while energy consumers discharge them in bursts - but does need to scale in terms of energy storage. It can also be placed somewhere where size and weight is not a significant concern; we happily store tens of thousands of tonnes of supplies for biomass, nuclear and fossil fuel plants, so storing similar amounts for long-term storage is fine. It's also OK to have a slow rate of change of power; you've got the short term storage to cover you as these things switch from charging to discharging, and thus it's fine for them to have response times comparable to coal or nuclear (18 to 36 hours to go from full charge rate to full discharge is fine).
However, what it does need is low self-discharge rates, since the goal is to charge whenever we have more energy available than we can use, and discharge when there's not enough energy. For example, charge on a cool and windy summer's day, when solar is providing the full energy needs over 24 hours, and the wind is "wasted", discharge in a dunkelflaute during a cold snap where we need lots of energy to keep people warm.
The three current top contenders for this niche are:
And of these contenders, note that the two that involve hydrogen run a substantial human risk; it's easy to substitute grey hydrogen (made by steam reformation of fossil fuels, releasing the CO2 into the atmosphere) for green hydrogen, such that there's no actual benefit in terms of the climate, but saving money for the people who do this.
There's also the possibility of a miracle in terms of low self-discharge sodium-ion or lithium-ion batteries, or a completely new tech that nobody's thought of yet. But it's unwise to consider a miracle likely :-)
Posted Feb 27, 2025 13:04 UTC (Thu)
by PeeWee (guest, #175777)
[Link] (12 responses)
I have yet to see a serious and honest calculation for *all* the demand. The easiest mistake is to just take current *electricity* demand and calculate how much renewables are needed to satisfy it. But that is only a fraction of what we actually need if we want to get rid of all fossil fuels - and no, burning trees is not green ("renewable" being the latest lie that just *sounds* like "green") and not sustainable; people should have listened instead of sleeping through History lessons in school.
And *then* we can start thinking about efficiencies and the price (also and most importantly: energetically) of storage solutions and materials.
Posted Feb 27, 2025 13:22 UTC (Thu)
by jjs (guest, #10315)
[Link] (10 responses)
Yea, renewables can do it.
Also, remember that roughly 2/3 of primary power is thrown away as waste heat. We won't be doing that as we electrify, since we don't have the inefficiencies of fossil fuel burning, so it's even better.
Yea, renewables can do it.
Posted Feb 27, 2025 13:41 UTC (Thu)
by farnz (subscriber, #17727)
[Link]
Technologically, this is entirely possible; the limiting factors are economic and political. And note that wind power ends up capturing some of the insolation over the sea, since the energy from that insolation drives air pressure shifts.
I'm also completely ignoring geothermal (where practical) and biomass (since determining how much biomass is genuinely renewable, and how much is unsustainable, is a hard problem). These do contribute something, but we don't need them to be confident that we can meet our needs on renewables.
Posted Feb 27, 2025 13:56 UTC (Thu)
by malmedal (subscriber, #56172)
[Link]
Looks like just about every country can get the energy they need with renewables within their own borders.
Posted Feb 27, 2025 14:12 UTC (Thu)
by PeeWee (guest, #175777)
[Link] (7 responses)
And that's not counting the concurrency with other uses of the land, like such minor matters as agriculture, which also still relies heavily on industrially produced fertilizers from finite resources with high energy inputs. Once those resources run out there will only be one way to scale food production and that is by increasing the area demand - guess why one Bill Gates is investing heavily in farm land. And yes, I know that certain researchers claim that solar cells can be built atop agriculture, in total disregard of feasibility.
There are also huge swaths of land that are simply inaccessible to humans, let alone endeavors like solar or wind parks, e.g. mountains, the (Ant)arktis, Siberia whose permafrost regions are thawing, making the ground miry which prohibits any building activity, huge swaths of Canada, etc. And that's just the northern hemisphere; rainforests and the likes are also off limits, if one does not want to throw out the baby with the bath water or cast out the devil with Satan's help. I think it is safe to say that the remainder of the Earth's surface has been captured already for other uses, like living and supporting human life, e.g. agriculture. As I said, I want an honest, preferably worst case calculation, of what is actually achievable and not some rosy number juggling. I remember an Energy Technology professor of mine - yes, I know a thing or two about the matter as well - gushing about that solar Gigapark - IIRC 100km * 100km - in the Sahara that would cover all human energy needs. Look how that turned out; keyword: Desertec. Plus, that is just another example of neocolonialism where Africa and the likes are just about good enough to serve *our* needs and can sod off when it comes to *theirs*.
Posted Feb 27, 2025 14:24 UTC (Thu)
by farnz (subscriber, #17727)
[Link] (3 responses)
We also need to fix the political and social mess created by the idea that energy supply needs to be under the control of big businesses, and not diffuse; one of the reasons we have such a huge problem is that fossil fuels are inherently not evenly distributed and accessible, and the entities that extract them have gained political power from doing so. Desertec is a typical example of not trying to fix this - because a big entity that makes money from Africa is more politically palatable than every home generating some power, and paying to share resources with each other.
Posted Feb 27, 2025 14:35 UTC (Thu)
by paulj (subscriber, #341)
[Link] (2 responses)
Posted Feb 27, 2025 14:41 UTC (Thu)
by farnz (subscriber, #17727)
[Link]
Maximally efficient use of land for solar power is incompatible with farmland, since that needs large panels; fortunately, we can get all the energy we need by only using rooftops for power, so for farmland, you're using the panels where you would otherwise have put up structures anyway.
Posted Feb 27, 2025 14:45 UTC (Thu)
by corbet (editor, #1)
[Link]
But all of this is getting pretty far off the original topic. There are plenty of places to discuss these issues, but I don't think this is what most folks come to LWN for, so maybe we can wind it down, please?
Posted Feb 27, 2025 14:34 UTC (Thu)
by jjs (guest, #10315)
[Link] (2 responses)
Concurrency of use - solar panels on roofs (residential and commercial solar), agrivoltaics (solar on farms, which actually can provide benefits to the farming side, as well as a source of income for the farmers), most wind farms are on actual farm land - the owner continues to farm/ranch around the wind turbines, because the majority of the land for a wind farm is to space out the turbines so they don't interfere with each other. Again, a source of guaranteed income to the farmers.
Yes, there's areas that are inaccessible. Simple answer - don't put your power production there. When you need less than 1% of the land to power the world, you have a lot of options.
Posted Feb 27, 2025 14:51 UTC (Thu)
by farnz (subscriber, #17727)
[Link] (1 responses)
For example, wind farms are also used to provide wind breaks for structures in the area; one of the things that the climate crisis has caused is stronger winds, and if you can extract energy from that wind (turning into electricity), you get storms that match historical norms, instead of stronger storms, reducing the damage done. The only issue then is accepting that the wind farms (and solar panels on farmland, and so on) are set up with electricity generation as a secondary thing, not as their primary goal; it's something you get "for free" when you solve the primary problem (like needing to shade part of a field, or protect a village from storms), and thus being bad at electricity generation is A-OK.
Posted Feb 27, 2025 15:41 UTC (Thu)
by Wol (subscriber, #4433)
[Link]
And then coppiced woodland (and many rotational farming schemes) are incredibly efficient and bio-diverse, both at the same time ...
Cheers
Posted Feb 27, 2025 23:34 UTC (Thu)
by intgr (subscriber, #39733)
[Link]
This is a common misconception. The majority of Iceland's energy comes from hydropower (~80%), not geothermal.
Posted Feb 27, 2025 14:50 UTC (Thu)
by jjs (guest, #10315)
[Link]
From that:
Their types of pumped hydro:
Other: Interconnect to get around the area. Example: When was the last time the entirety of North America saw no wind or sun for weeks? I don't think it's happened.
Re hydrogen: I doubt it will be a factor in long term. Hydrogen is a terrible material for energy storage, due to the small size of the molecule, the poor volumetric energy density, and the fact it has to be created (i.e. the inefficiency of electrolysis, pumping, storage, and then conversion back to electricity via fuel cell). Also, all those steps have maintenance requirements, which are not small. Example: Fuel Cell bus maintenance costs around twice that of diesel bus maintenance costs for the same miles traveled.
You need to either do massive compression (which costs energy), cool it down to 20K (which takes energy), or use large volumes. And regardless of your storage, that small molecule gets out. NASA, who are experts with hydrogen, took 5 wet dress rehearsals to successfully fuel the Artemis mission. There's a reason all the commercial launch vehicles are going to either methalox or kerolox, instead of hydrolox.
Add in that it's a potent greenhouse gas (indirectly), and losses estimated around 1% for every connection in the pipeline, it's just not a great idea for energy. It's very useful for chemistry and chemical engineering. For energy? Not in my opinion.
Posted Feb 27, 2025 15:28 UTC (Thu)
by Wol (subscriber, #4433)
[Link]
Dunno how easy this is - a caustic solution and artificial chlorophyll. Pump surplus electric in, get methanol out. Given that we invented oil cracking not that long ago and made petrol as cheap as diesel using zeolites, is there any way we can bubble CO2 through a charged zeolite to give a similar effect?
Cheers,
Posted Feb 27, 2025 19:49 UTC (Thu)
by sfeam (subscriber, #2841)
[Link] (1 responses)
I may be missing something, and my perspective is probably skewed because I live in an area where most (>80%) of the electric power is hydroelectric, but isn't that niche already nicely filled by storing water in a reservoir in the winter when rain is plentiful and sunshine is not?
Posted Feb 27, 2025 20:48 UTC (Thu)
by malmedal (subscriber, #56172)
[Link]
Lithium-ion batteries self-discharge something like 0.3 to 3% per month, so you could store energy for quite some time.
At current prices, $50/kWh, they are very profitable when you get paid for a discharge every day. If you charged your batteries in summer and sold in winter you'd only get money once per year.
With flow-batteries, the reactants and tank-space promise to be less than a dollar for an extra kWh so it becomes economically feasible.
Posted Feb 27, 2025 21:13 UTC (Thu)
by Cyberax (✭ supporter ✭, #52523)
[Link] (1 responses)
The idea is that these kinds of batteries should be perfect for utility-scale energy storage. You can trivially scale the storage capacity just by adding more tanks, which is very cheap. Pumps with tubing are a fixed cost. BTW, regular li-ion batteries often also have pumps for liquid cooling.
Vanadium is also not really something terribly expensive. It's produced as a by-product of uranium refining, and there aren't that many uses for it, so it's pretty cheap. If it's successful, then its price might go up, but at the same time, there are plenty of reserves with vanadium ores that are not mined right now.
The devil is in the details, of course. I already wrote about problems with the membrane, but there are more issues. Electrochemistry is weird, and you usually end up with tons of side-reactions like peroxide production, that corrodes your electrodes. Vanadium chemistry is the most often investigated one because you're cycling between oxidation states of just one element, resulting in fewer side reactions.
So yeah, I don't think that they'll succeed, but it's not because the idea is meritless.
Posted Feb 28, 2025 9:58 UTC (Fri)
by farnz (subscriber, #17727)
[Link]
Of course, just because it's a really attractive answer doesn't mean it will turn out to be practical or usable. But I can see why the interest is there, and as long as it's not distracting from the bigger problem of ending fossil fuel use, there's no real issue with people experimenting in their "back yards".
Posted Feb 28, 2025 4:32 UTC (Fri)
by gdt (subscriber, #6284)
[Link]
Of course I could have made the battery twice as large, as your sums suggest. But why would I pay for twice as much battery for the same result?
Posted Feb 28, 2025 3:51 UTC (Fri)
by gdt (subscriber, #6284)
[Link] (1 responses)
It's reasonable to view the flow battery as being in the hobbyist or "early commercial attempts" stage which was experienced by the internal combustion engine. So far there's no show-stopper preventing a reasonable expectation of "further development" , but commercialisation is still a very speculative investment.
Posted Feb 28, 2025 21:35 UTC (Fri)
by kleptog (subscriber, #1183)
[Link]
The nice thing about these is that if you've got the storage part down pat, you can endlessly upgrade in place just by swapping out pumps and membranes.
If the argument is: they don't need to be commercially viable then you may be right. That's why China is running circles around us in battery technology. Because they invest in stuff to build up their technology base. Something we've forgotten how to do under the belief the invisible hand will magically solve our problems.
Posted Mar 3, 2025 22:17 UTC (Mon)
by chexo4 (subscriber, #169500)
[Link] (2 responses)
It seems like a much more repairable and safe solution than lithium ion batteries, which have this troublesome problem of burning much hotter than a regular car fire and so ferociously that some fire departments have to take a crane and dump the car in a dumpster/tank full of water to fully submerge it (because otherwise it stays on fire no matter how much water you spray it with)
Plus it maintains the skill set of mechanics/automobile technicians what with managing small pumps and fluids and such. “Hey, your car is due for new electrolyte fluid!”
Posted Mar 3, 2025 22:54 UTC (Mon)
by malmedal (subscriber, #56172)
[Link]
Posted Mar 4, 2025 10:11 UTC (Tue)
by farnz (subscriber, #17727)
[Link]
Posted Mar 7, 2025 20:52 UTC (Fri)
by NZheretic (guest, #409)
[Link] (10 responses)
No pump needed, no flexible plumbing needed. all that flexes is the electrical leads.
Scale by adding more units.
Posted Mar 7, 2025 21:37 UTC (Fri)
by Cyberax (✭ supporter ✭, #52523)
[Link] (9 responses)
Posted Mar 7, 2025 21:49 UTC (Fri)
by NZheretic (guest, #409)
[Link] (8 responses)
Victorian engineering for the 21st Century.
Posted Mar 8, 2025 0:29 UTC (Sat)
by Cyberax (✭ supporter ✭, #52523)
[Link] (7 responses)
Posted Mar 11, 2025 1:14 UTC (Tue)
by NZheretic (guest, #409)
[Link] (6 responses)
Posted Mar 11, 2025 2:32 UTC (Tue)
by Cyberax (✭ supporter ✭, #52523)
[Link] (5 responses)
Posted Mar 11, 2025 11:23 UTC (Tue)
by daroc (editor, #160859)
[Link] (4 responses)
I don't know whether this idea is really a better design or not; it certainly sounds plausible to me, as someone with no experience whatsoever in flow battery design. Maybe it's a good enough idea that the experts will try it, and then we'll know for sure.
But it's definitely not a perpetual motion machine.
Posted Mar 11, 2025 20:46 UTC (Tue)
by Cyberax (✭ supporter ✭, #52523)
[Link] (3 responses)
And to do that, you need to rotate the tanks weighing several tons. This will require a MASSIVE gearbox to bear the load.
Posted Mar 11, 2025 21:22 UTC (Tue)
by Wol (subscriber, #4433)
[Link] (2 responses)
And why's that a problem? A bit different, but there's Jodrell bank - massive bearings.
Or a lot closer - the Falkirk Wheel. Okay, those caissons are balanced, I don't know what effect unbalanced caissons would have, but an interesting fact about the Wheel - a 180 degree revolution uses less energy than boiling a kettle ...
Cheers,
Posted Mar 12, 2025 20:55 UTC (Wed)
by NZheretic (guest, #409)
[Link]
Posted Mar 12, 2025 21:11 UTC (Wed)
by Cyberax (✭ supporter ✭, #52523)
[Link]
In contrast, a pump capable of pumping several liters per second costs less than $100. A corrosion resistant pump is going to be more expensive, but not by much.
Good luck
Good luck
Good luck
Good luck
Good luck
Wol
Good luck
Good luck
Wol
Good luck
Good luck
Good luck
Wol
Good luck
Good luck
Good luck
You're looking at the single-cycle latency limit, and asserting that it's impossible for the motherboard to cope with multi-cycle latencies. In practice, we can happily use gigahertz signals over kilometers of distance (such as in mobile phone networks) by "pipelining"; you send a request signal, knowing that the response to the signal you've just sent will be multiple clock cycles later. Even better, as long as you allow for propagation delays, you can send a sequence of signals (timed by the clock), to be handled by the remote end as they arrive, in a "pipelined" fashion.
That ignores pipelining
That ignores pipelining
That's what I was getting at when I wrote:
That ignores pipelining
Where size becomes an issue is where latencies are critical - if a device is small, everything can be assumed to happen in a single clock cycle, but as the scale increases, the minimum latency also increases. You thus have an extra layer of complexity when clocks increase, because you can no longer place devices freely; you have to allow for latency issues.
That ignores pipelining
That ignores pipelining
Optimizing for stationary power storage vs. mobile (vehicles, planes, etc.)
Optimizing for stationary power storage vs. mobile (vehicles, planes, etc.)
No wonder all commercial efforts have failed
10kWh/(.6 * 20 kWh/t) = 833 kg ≃ 1 t
(efficiency = .6; energy density (Vanadium-Redox-Flow-Battery) = 20 kWh/t)
(rounded gratuitously to keep the numbers simple for establishing a baseline order of magnitude)
The presentation says nothing about the power part: how many cells of what size and weight would be needed to provide 21 kW power potential? Also, at 21 kW this thing would not last half an hour, so don't even think about charging an electric car - another of those tech lies - with such low capacity. But I think we don't need to dig deeper given the above sobering estimation.
No wonder all commercial efforts have failed
No wonder all commercial efforts have failed
No wonder all commercial efforts have failed
No wonder all commercial efforts have failed
No wonder all commercial efforts have failed
No wonder all commercial efforts have failed
No wonder all commercial efforts have failed
No wonder all commercial efforts have failed
No wonder all commercial efforts have failed
10 years ago, you'd have been saying "how much could I have achieved if we designed for LiNMC instead of LFP?". LFP was an expensive option compared to NMC, with lower energy and power densities and a shorter lifetime. In theory, however, LFP could offer a much longer lifetime than NMC cells, and in the last 5 years, that's been commercially demonstrated.
No wonder all commercial efforts have failed
No wonder all commercial efforts have failed
- Many are already in production
- In theory, they take 10 times more space. But much less in practice because lithium batteries must be spaced for when they catch fire.
No wonder all commercial efforts have failed
- There seems to be many different types of flow batteries with a wide range of price points
- The upfront cost can be misleading because Lithium batteries degrade much more rapidly; after only a few hundreds cycles
No wonder all commercial efforts have failed
No wonder all commercial efforts have failed
No wonder all commercial efforts have failed
Grid operators would go out of business with lots of net metering
(electricity price) = (electricity price) + (operating costs to include maintenance & upgrades of grid) + (profit)
Grid operators would go out of business with lots of net metering
Grid operators would go out of business with lots of net metering
Grid operators would go out of business with lots of net metering
Grid operators would go out of business with lots of net metering
Grid operators would go out of business with lots of net metering
Wol
No wonder all commercial efforts have failed
Disclaimer: this is my field of work, so I'm not unbiased here - I work on renewable generation and lithium-ion battery storage systems.
The "missing piece" in renewable energy
The "missing piece" in renewable energy
Just take electric cars which easily blow the electricity demand of a household to at least double of the status quo, so much even that in Germany an electric utility company had a field test, what would happen if all cars in a test neighborhood were electric, only to find out that the grid cannot deliver that additional demand without expensive load balancing solutions.
Next is heating and not only households but on an industrial scale, which makes households pale in comparison every time. Guess why Island is the prime supplier of Aluminium; because they have geothermal electricity to burn, quite literally. Now you do the math, what happens if and when all industrial scale energy guzzlers, like Aluminium/Steel/Concrete/etc. works run on electricity instead of coal or gas or whatever non-sustainable source.
Yes, renewables can power all human energy requirements
Just to extend the calculations further; a bit over 1.5% of the land area is built-up urban land. We need about 0.2% of the land area to have current solar panels over it to produce as much electricity as we currently get from all sources, including fossil sources - that means that we need about 15% of built-up land to be covered in solar panels, ignoring wind (as the other significant renewable source). And that's enough that solar alone, averaged over 12 months, covers all our current energy production; wind and increased coverage of built-up land lets us go for more profligate uses of energy.
Yes, renewables can power all human energy requirements
Yes, renewables can power all human energy requirements
Yes, renewables can power all human energy requirements
We only need to cover all roofs in the world with current solar panels to meet global energy needs, and build up electricity grids to move energy from where it's being produced to where it's being demanded; we benefit from solar panels over farmland because they protect from weather (although you inherently have to reduce the areal efficiency of the solar farm by spreading the panes out since you need to ensure that enough light gets past the panels to the ground below).
Yes, renewables can power all human energy requirements
Yes, renewables can power all human energy requirements
Depends on the crop; solar panels over farmland should be implemented as a "farmland first" sort of deal, where you place the panels to shade areas that get too much sunlight, and to direct rainfall to where the plants can make most use of it.
Yes, renewables can power all human energy requirements
There is a growing "solar garden" movement here trying to prove that assertion wrong.
Yes, renewables can power all human energy requirements
Yes, renewables can power all human energy requirements
Especially in the context that over 1.5% of land is built-up (cities and towns); we're in the fortunate position that everything other than solar panels on the roof is not needed to meet our annual energy needs from solar, "merely" to provide diversity of supply and reduce the need for energy storage, and thus you can use it in places where the energy generation is secondary.
Yes, renewables can power all human energy requirements
Yes, renewables can power all human energy requirements
Wol
The "missing piece" in renewable energy
Long term storage options
"Our Atlases currently contain 820,000 non-overlapping sites with 86 million GWh of energy storage potential which is equivalent to about 2 trillion EV batteries. Most of the Atlas sites are off-river and do not require any new dams on rivers. Land and water use is very low. PHES constitutes >90% of electricity storage worldwide because of its low cost. Batteries are preferred for storage of seconds to hours, and PHES for overnight and longer."
Type Unprotected Area Atlas Protected Area Atlas Explanation
Greenfield Unprotected Areas Protected Areas Two new reservoirs
Bluefield Unprotected Areas Protected Areas At least one existing reservoir
Brownfield Unprotected Areas Protected Areas Repurpose mining sites for pumped hydro reservoirs
Ocean Unprotected Areas Protected Areas Use the ocean for the lower reservoir
Seasonal Unprotected Areas Protected Areas Store water for longer periods
Turkey’s Nest Unprotected Areas Protected Areas Create PHES reservoirs on flat ground, for more siting options
The "missing piece" in renewable energy
Wol
"This leaves us with a niche to fill; we need something that can absorb energy when we have excess renewables available for more than 24 hours, and then release it months later when renewables hit what the Germans call a "dunkelflaute" - insufficient insolation and no wind over a long period, causing a shortfall in energy - and this niche is where flow batteries are interesting."The "missing piece" in renewable energy
The "missing piece" in renewable energy
No wonder all commercial efforts have failed
Also worth noting that flow batteries provide a potential answer for places like the extreme north of Alaska, which currently generate electricity from imported diesel. If you could have a setup where what renewables you get extend the battery runtime, and you refuel the battery the way you currently refuel the generator (but taking away the "drained" fluid to recharge elsewhere), that'd be really attractive.
No wonder all commercial efforts have failed
No wonder all commercial efforts have failed
Development of new supply takes time
Development of new supply takes time
I wonder if flow batteries could be used in electric vehicles
I wonder if flow batteries could be used in electric vehicles
The weight and size issues of flow batteries make them impractical for mobile applications - for a given energy and power target, a flow battery is bigger and heavier than lithium ion or experimental sodium ion batteries. Their big advantage is a very low self-discharge rate, which in theory would make them a good choice for long-term storage (assuming the practical problems around the chemicals destroying tubing, pumps and membranes can be solved); their secondary benefit is that you can move the energy around as a tanker full of liquid, instead of as a solid battery, and we have good solutions to moving large volumes of dangerous liquids around.
I wonder if flow batteries could be used in electric vehicles
Instead of pumps use gravity.
Instead of pumps use gravity.
Just a matter of gearing & division.
Just a matter of gearing & division.
Just a matter of gearing & division.
Just a matter of gearing & division.
Just a matter of gearing & division.
Just a matter of gearing & division.
Just a matter of gearing & division.
Wol
Just a matter of gearing & division.
Just a matter of gearing & division.